The present invention is directed to a bur gripping mechanism for use in a high speed dental handpiece. Various systems are known and are commonly used for releasably holding dental burs in place. They include collet chucks of both the pushout and drawback types, and spring grip chucks.
In the present invention, the traditional chuck is eliminated in favor of a ball-type gripping mechanism providing a positive gripping engagement with the shank of a dental bur. Gripping balls are carried in a ball carrier which surrounds the bur shank. The ball carrier is seated on a spring which urges the ball carrier and its entrained balls into operative engagement with the inner wall of a conical or tapered ramp, which surrounds the ball carrier and which in turn forces the balls inward against the bur shank. The balls indent the softer material of the bur shank for positive engagement. An externally applied force on the ball carrier against the spring releases the balls from engagement with the bur shank.